let inputs and textareas follow theme coloring (#499)

Fixes bad contrast in dark mode at, e.g., /numeric-inputs

Author: rdickert

content/tutorial/common/src/app.html

@@ -121,6 +121,7 @@
 			input,
 			textarea {
 				background: var(--bg-1);
+				color: inherit;
 			}
 
 			select:not([multiple]) {